A higher level of Ki-67 means that the cancer cells are multiplying at a faster rate.
Use of the Ki-67 test in breast cancer remains controversial.
What Is the Ki-67 Protein?
Verywell / Madelyn Goodnight
Normal living cells divide in two to produce new cells.
If the cells continue to mutate and rapidly divide, they can become cancerous.
Thus, a higher-than-normal volume of Ki-67 means that cells are dividing at an abnormal rate.
Your oncologist will request different tests, and you will get your results in apathology report.
The test uses anantibodythat attaches toantigenreceptors on the Ki-67 protein.
While healthcare providers increasingly order the Ki-67 proliferation marker test, its overall benefit is not certain.
Research is underway to determine how to best apply the information from the test to patient care.
Currently, doctors disagree on how to use the test results to guide cancer treatment.
The test may help determine your cancer prognosis or your chance of recovery.
Your oncologist usually takes several test results into account when trying to understand your unique cancer.
There is ongoing research to better understand how to use and apply this information to patient care.
Chemotherapy attacks all rapidly growing cells (including healthy cells, such as hair follicles).
Therefore, tumors that are more aggressive (divide more rapidly) may respond particularly well to these regimens.
Luminal A vs. Luminal B
There are many types of breast cancer.
Oncologists recommend treatment based on several different characteristics of the cancer cells.
Often, doctors will look at the genes of the cancer cells to better identify and treat the disease.
There are several different groupings of cancer types, known as luminal groups.
Ki-67 has been used as part of the data to separate tumors into these two categories.
There are many other tests being studied to help with this classification system.
Scientists are studying the genetic makeup of cancer hoping to better understand will lead to more effective treatments.
This is the percentage of the total sample that has active Ki-67 proteins.
Even though it can be helpful, not all healthcare providers order the Ki-67 test.
Do not be alarmed if it is not on your pathology report.
Your healthcare team will look at the overall results from all of your tests to assess your breast tumor.
There are other tests that researchers are developing to help understand how cancer behaves.
For example, a different test used to assess the growth of breast cancer is called the S-phase fraction.
The test measures how many cancer cells are in the process of copying their DNA.
This test is also reported as a percentage of the cells.
For this test, a percentage greater than 10 is considered high.
The overall importance of Ki-67 as a marker and prognostic factor in breast cancer remains undetermined and somewhat controversial.
Many researchers support the use ofneoadjuvant(before surgery) chemotherapy for those with Ki-67 results above 20%.
It is likely that guidelines and use of Ki-67 will change over time as more research is done.
Get our printable guide for your next healthcare provider’s appointment to help you ask the right questions.
Summary
Tumor markers can help doctors understand the stage, growth, and seriousness of your cancer.
Ki-67 is a biomarker test for people with breast cancer.
It is one of many different tests available.
Cancer research continues to help medical professionals make the best decisions they can when developing treatment plans.
Frequently Asked Questions
Cancer cells do not obey the normal signals to stop growing.
They continue to grow and divide in situations in which healthy cells would stop growing.
Proliferation is a word to describe the way cancer cells grow and multiply.
Each person with breast cancer needs an individualized treatment plan from their healthcare team.
Overall, a low Ki-67 generally means a less aggressive cancer.
2021;113(7):808-819. doi:10.1093/jnci/djaa201
Breastcancer.org.Understanding your pathology report.
132(3):895-915. doi:10.1007/s10549-011-1837-z
